Tools available on the market come in the following categories:                cup brushes        circular brushes        miscellaneous types for hobby applications        linear brushes (known as “strip brushes”) for miscellaneous applications.        
In this context, a prior art brush typically comprises a brush body and a plurality of filaments having a first portion mechanically anchored to the brush body and a second portion designed to apply a brushing action when the brush body is rotated about its axis, or used as retaining elements.
As regards the “active” portion of the brush, that is, the filaments, these are normally wound around rings and may be metal filaments (that is, twisted tufts or crimped wire), synthetic filaments (straight or crimped) and natural filaments (horsehair and so on).
In twisted tuft brushes (with metal wires), the filaments are grouped in tufts and then twisted. Each tuft is associated with a hole made on the flange in the proximity of its outer circumference.
In crimped filament rings, the flange is called ferrule and acts in conjunction with a metal mounting ring around which the filaments are bent in the shape of U. To hold the filaments correctly in place, the ferrule is beaded on its cylindrical part.
Thus, the ferrule and the metal mounting ring (generally a metal ring) “grip” the filaments folded into a U shape and distributed all around the inner circumference of the mounting ring.
In the manufacture of a cup brush with crimped filaments, four elements are usually assembled, namely, an inner cup, an outer cup and a reducer (or clamping element) which by shaping the end of the reducer draws the ring with the filaments closer to the other elements packing them together to form a single body.
In some prior art brushes, the process ends by embedding the tool (by casting or injection moulding) partly or totally in a plastic material, usually polyurethane, plastic resins or the like.
In this production method, all the metal components forming part of the brush (flanges, cups, etc) are internally coated totally or partly by the plastic material or only the ring with the metal filaments is embedded in the plastic.
It should be noted that up to the present, this process has been applied only to brushes with metal filaments for the following reasons:                safety, because the filaments do not reach breaking point during brushing operations;        brushing efficacy, because the brushes are kept as far as possible in a straight position making their brushing action more effective.        
All the brushes currently made according to this production system have several drawbacks.
In effect, brushes made in this way tend to produce a high concentration of heat at the brush body, that is, in the part opposite to the active filament portion. In the case of brush bodies made entirely of plastic, this heat leads to quick deterioration of the properties of the plastic matrix, causing the plastic to crumble and the filaments to break quickly (because they are not held properly in place by the plastic).
Moreover, this excessive heating also creates the risk of contaminating the brushed surface.
Furthermore, current brushes with synthetic filaments with abrasive powders not totally embedded in plastic materials have the drawback that they lose the abrasive powder during brushing, causing rapid wear of the moving mechanical parts.